package com.android.measuringimportanceoflectureslides.Camera;

import java.io.IOException;
import java.util.List;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;

public class PreviewView extends ViewGroup implements SurfaceHolder.Callback {
	private final String TAG = "Preview";

	private SurfaceHolder mHolder;
	private SurfaceView mSurfaceView;
	private Size mPreviewSize;

	private PreviewSizeChangedCallback mPreviewSizeChangedCallback = null;

	private Camera mCamera;
	private List<Size> mSupportedPreviewSizes;

	public interface PreviewSizeChangedCallback {
		void previewSizeChanged();
	}

	public PreviewView(Context context, AttributeSet attrs) {
		super(context, attrs);
		mSurfaceView = new SurfaceView(context, attrs);
		addView(mSurfaceView);
		// Install a SurfaceHolder.Callback so we get notified when the
		// underlying surface is created and destroyed.
		mHolder = mSurfaceView.getHolder();
		mHolder.addCallback(this);
		mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
	}

	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		if (changed && getChildCount() > 0) {
			final View child = getChildAt(0);

			final int width = r - l;
			final int height = b - t;

			int previewWidth = width;
			int previewHeight = height;
			
			if (mPreviewSize != null) {
				previewWidth = mPreviewSize.width;
				previewHeight = mPreviewSize.height;
			}

			// Center the child SurfaceView within the parent.
			if (width * previewHeight > height * previewWidth) {
				final int scaledChildWidth = previewWidth * height
						/ previewHeight;
				child.layout((width - scaledChildWidth) / 2, 0,
						(width + scaledChildWidth) / 2, height);
			} else {
				final int scaledChildHeight = previewHeight * width
						/ previewWidth;
				child.layout(0, (height - scaledChildHeight) / 2, width,
						(height + scaledChildHeight) / 2);
			}
		}

	}

	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		// We purposely disregard child measurements because act as a
		// wrapper to a SurfaceView that centers the camera preview instead
		// of stretching it.
		final int width = resolveSize(getSuggestedMinimumWidth(),
				widthMeasureSpec);
		final int height = resolveSize(getSuggestedMinimumHeight(),
				heightMeasureSpec);
		setMeasuredDimension(width, height);

		if (mSupportedPreviewSizes != null) {
			mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width,
					height);
		}
	}

	public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        if (mCamera != null) {
            // Now that the size is known, set up the camera parameters and
            // begin
            // the preview.
            Camera.Parameters parameters = mCamera.getParameters();
            parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
            requestLayout();

            try
            {
                mCamera.setParameters(parameters);
            }
            catch (RuntimeException e)
            {
                Log.e(TAG, "error setting parameters", e);
            }

            mCamera.startPreview();
            if (mPreviewSizeChangedCallback != null) {
                mPreviewSizeChangedCallback.previewSizeChanged();
            }
        }
    }

	public void surfaceCreated(SurfaceHolder holder) {
		try {
			if (mCamera != null) {
				mCamera.setPreviewDisplay(holder);
			}
		} catch (IOException exception) {
			Log.e(VIEW_LOG_TAG, "IOException caused by setPreviewDisplay()",
					exception);
		}
	}

	public void surfaceDestroyed(SurfaceHolder holder) {
		if (mCamera != null) {
			mCamera.stopPreview();
		}
	}

	private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
		final double ASPECT_TOLERANCE = 0.1;
		double targetRatio = (double) w / h;
		if (sizes == null)
			return null;

		Size optimalSize = null;
		double minDiff = Double.MAX_VALUE;

		int targetHeight = h;

		// Try to find an size match aspect ratio and size
		for (Size size : sizes) {
			double ratio = (double) size.width / size.height;
			if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
				continue;
			if (Math.abs(size.height - targetHeight) < minDiff) {
				optimalSize = size;
				minDiff = Math.abs(size.height - targetHeight);
			}
		}
		// Cannot find the one match the aspect ratio, ignore the requirement
		if (optimalSize == null) {
			minDiff = Double.MAX_VALUE;
			for (Size size : sizes) {
				if (Math.abs(size.height - targetHeight) < minDiff) {
					optimalSize = size;
					minDiff = Math.abs(size.height - targetHeight);
				}
			}
		}
		return optimalSize;
	}

	public void setPreviewSizeChangedCallback(PreviewSizeChangedCallback callback) {
		mPreviewSizeChangedCallback = callback;
	}

	public void setCamera(Camera camera) {
		mCamera = camera;
		if (mCamera != null) {
			mSupportedPreviewSizes = mCamera.getParameters()
					.getSupportedPreviewSizes();
			requestLayout();
		}
	}

}
